DYNAMIC SIGNAL TRANSMISSION STRUCTURE AND BEAMFORMING METHOD

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First Claim
1. A dynamic signal transmission structure based on a hybrid beamforming technology, comprising a radiofrequency module and an antenna array connected with the radiofrequency module, wherein:
 the radiofrequency module comprises one or more radiofrequency link units connected in parallel;
the antenna array comprises one or more antenna subarrays, and each said antenna subarray is connected with one of said radiofrequency modules;
the hybrid beamforming technology comprises analog beamforming and digital beamforming; and
in the structure, analog beamforming parameters and digital beamforming parameters are constant, and the number of the radiofrequency link units in the radiofrequency module, the number of the antenna subarrays in the antenna array, the analog beamforming parameters and the digital beamforming parameters are in a quantitative relation.
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Abstract
A dynamic signal transmission structure based on a hybrid beamforming technology includes a radiofrequency module and an antenna array connected therewith. The radiofrequency module includes one or more radiofrequency link units connected in parallel, the antenna array includes one or more antenna subarrays, and each antenna subarray is connected with one of the radiofrequency modules. The hybrid beamforming technology includes analog and digital beamforming. In this structure, the analog beamforming parameters and the digital beamforming parameters are constant, and the number of radiofrequency link units in the radiofrequency module, the number of antenna subarrays in the antenna array, the analog beamforming parameters, and the digital beamforming parameters are in a quantitative relation. The structure of the antenna array and the number of radiofrequency link units in each radiofrequency module can be adjusted dynamically under the condition where the performance is guaranteed, and accordingly, the hardware complexity is reduced.
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10 Claims
 1. A dynamic signal transmission structure based on a hybrid beamforming technology, comprising a radiofrequency module and an antenna array connected with the radiofrequency module, wherein:
the radiofrequency module comprises one or more radiofrequency link units connected in parallel; the antenna array comprises one or more antenna subarrays, and each said antenna subarray is connected with one of said radiofrequency modules; the hybrid beamforming technology comprises analog beamforming and digital beamforming; and in the structure, analog beamforming parameters and digital beamforming parameters are constant, and the number of the radiofrequency link units in the radiofrequency module, the number of the antenna subarrays in the antenna array, the analog beamforming parameters and the digital beamforming parameters are in a quantitative relation.  View Dependent Claims (2, 3)
 4. A beamforming method, comprising:
designing an antenna array, and dividing the antenna array into one or more antenna subarrays, wherein each said antenna subarray is controlled by a radiofrequency module; determining the number of radiofrequency link units in the radiofrequency module; establishing a channel model of a required frequency band of electromagnetic waves; obtaining analog beamforming parameters and digital beamforming parameters by calculation according to a channel matrix in the channel model; and carrying out beamforming according to the analog beamforming parameters and the digital beamforming parameters.  View Dependent Claims (5, 6, 7, 8, 9, 10)
1 Specification
The invention relates to the technical field of communication, in particular to a dynamic signal transmission structure and a beamforming method.
Nowadays, most frequency bands used for wireless mobile communication are microwave frequency bands from 300 MHz to 30 GHz, and due to the insufficiency of the frequency spectrums in use, the achievable maximum wirelesscommunication speed is limited. Millimeterwave carrier spectrums and terahertz carrier spectrums having the bandwidths of tens of GHz, hundreds of GHz, and even thousands of GHz can meet the demands of the market for ultrahigh transmission speeds in the next decade, and can adapt to the sharp increase of wireless communication data at present.
As for the shortwavelength characteristic of the terahertz frequency bands, beamforming technologies can be adopted to increase the transmission distances and transmission speeds of millimeterwave electromagnetic waves and terahertz electromagnetic waves. Existing beamforming technologies include a fulldigital beamforming technology and a fullanalog beamforming technology, wherein the hardware complexity of signal transmission structure formed on the basis of the fulldigital beamforming technology is excessively high, and the performance of a signal transmission structure formed on the basis of the fullanalog beamforming technology has its drawbacks, and consequentially, reduction of the hardware complexity and improvement of the performance of the signal transmission structure cannot be realized at the same time.
To settle the abovementioned issues, it'"'"'s necessary to provide a dynamic signal transmission structure and a beamforming method to simplify a hardware structure and to realize desired performance.
A dynamic signal transmission structure based on a hybrid beamforming technology comprises a radiofrequency module and an antenna array connected with the radiofrequency module, wherein:
The radiofrequency module comprises one or more radiofrequency link units connected in parallel;
The antenna array comprises one or more antenna subarrays, and each antenna subarray is connected with one of radiofrequency modules;
The hybrid beamforming technology comprises analog beamforming and digital beamforming; and
In this structure, the analog beamforming parameters and the digital beamforming parameters are constant, and the number of the radiofrequency link units in the radiofrequency module, the number of the antenna subarrays in the antenna array, the analog beamforming parameters, and the digital beamforming parameters are in a quantitative relation.
In one embodiment, the antenna subarray comprises a plurality of antennae, each radiofrequency link unit in the radiofrequency module is connected with each antenna in the corresponding antenna subarray, and a modulator is connected in series between each radiofrequency link unit in the radiofrequency module and each antenna in the corresponding antenna subarray.
In one embodiment, the modulator is a phase shifter.
In this structure, under the condition where beamforming parameters are constant, the hardware complexity can be reduced by dynamically adjusting the structure of the antenna arrays and the number of the radiofrequency link units in each radiofrequency module, namely by changing the values of m and n, without changing the performance.
A beamforming method comprises the following steps:
Designing an antenna array, and dividing the antenna array into one or more antenna subarrays, wherein each antenna subarray is controlled by one radiofrequency module;
Determining the number of radiofrequency link units in the radiofrequency module;
Establishing a channel model of a frequency band of electromagnetic waves;
Obtaining analog beamforming parameters and digital beamforming parameters by calculation according to a channel matrix in the channel model; and
Carrying out beamforming according to the analogbeamforming parameters and digitalbeamforming parameters.
In one embodiment, the step of obtaining the analog beamforming parameters and the digital beamforming parameters by calculation according to the channel matrix in the channel model comprises the following steps:
Carrying out singular value decomposition on the channel matrix in the channel model to obtain a solution to a right singularvalue matrix; and
Obtaining the analog beamforming parameters and the digital beamforming parameters by calculation according to the solution to the right singularvalue matrix.
In one embodiment, the analog beamforming parameters and the digital beamforming parameters are obtained by calculation according to the solution to the right singularvalue matrix based on a sparse coding algorithm.
In one embodiment, the maximum frequency spectral efficiency of hybrid beamforming of the dynamic signal transmission structure is solved to obtain a relation between the solution to the right singularvalue matrix, and the analog beamforming parameters and the digital beamforming parameters.
In one embodiment, an algorithm for solving the maximum frequency spectral efficiency of hybrid beamforming of the dynamic signal transmission structure is obtained based on an actual transmission signal, a precoded and combined equivalent channel, and a combined noise covariance matrix.
In one embodiment, the channel model of the frequency band of the electromagnetic waves is established based on a ray tracing technology.
In one embodiment, the channel model of the frequency band of the electromagnetic waves is a multiuser, multiinput and multioutput channel model.
According to the beamforming method mentioned above, the beamforming parameters capable of maximizing the performance of the dynamic signal transmission structure are worked out according to preset hardware parameters, beamforming is carried out based on the beamforming parameters, and the structure of the antenna array in the dynamic signal transmission structure and the number of the radiofrequency link units in each radiofrequency module can be adjusted dynamically to obtain a dynamic signal transmission structure with the hardware complexity lower than the fulldigital beamforming technology, and having the performance approximate to the fulldigital beamforming technology.
In order to more clearly explain the technical solutions of the embodiments of this application or the prior art, the drawings to be used for the description of this embodiments or the prior art are briefly introduced as follows. Clearly, the drawings in the following description are only illustrative ones of this application, and those ordinarily skilled in this field can acquire drawings of other embodiments according to these illustrative ones without creative labor.
For a better understanding of the objectives, technical solutions, and advantages of the invention, the invention is further expounded below with reference to the accompanying drawings and embodiments. It would be appreciated that the embodiments described here are used for explaining the invention only, but are not for the purpose of limiting the invention.
A dynamic signal transmission structure is based on a hybrid beamforming technology which comprises analog beamforming and digital beamforming. In this dynamic signal transmission structure, analogbeamforming parameters and digitalbeamforming parameters are constant, and the number of radiofrequency link units in a radiofrequency module 100, the number of antenna subarrays 201 in an antenna array 200, the analog beamforming parameters, and the digital beamforming parameters are in a quantitative relation.
As shown in
The radiofrequency module 100 comprises n radiofrequency link units connected in parallel; the antenna array 200 comprises in antenna subarrays 201, and each antenna subarray 201 is connected with one radiofrequency module 100; and the radiofrequency link units in the radiofrequency module 100 and the antenna subarrays 201 in the antenna array 200 are in a quantitative relation.
According to actual needs, users can preset the value of the number m of the antenna subarrays, and then the value of the number n of the radiofrequency link units in the each radiofrequency module 100 can be obtained by calculation; or the users can preset the value of the number n of the radiofrequency link units in each radiofrequency module 100, and then the value of the number m of the antenna subarrays in the antenna array 200 can be obtained by calculation. In this way, the structure of the antenna array and the number of the radiofrequency link units in each radiofrequency module can be adjusted dynamically under the condition where the performance of the structure is guaranteed, and accordingly, the hardware complexity is reduced.
Specifically, the total number Nt of antennae in the antenna array is a preset value, the radiofrequency module 100 comprises n radiofrequency link units, the antenna array 200 comprises in antenna subarrays 201, and each antenna subarray 201 is connected with one radiofrequency module 100, namely, the total number Lt of the radiofrequency link units meets Lt=m*n.
In one embodiment, as shown in
In a signal transmission structure based on the fulldigital beamforming technology, Lt=Nt.
In one embodiment, as shown in
In one embodiment, as shown in
In one embodiment, as shown in
In the dynamic signal transmission structure, the total number of the radiofrequency link units is Lt/Nt times that of radiofrequency link units in the dynamic signal transmission structure based on the fulldigital beamforming technology.
Under the condition where the beamforming parameters are constant, the hardware complexity can be reduced by dynamically adjusting the structure of the antenna array and the number of the radiofrequency link units in each radiofrequency module, namely by changing the values of m and n, without changing the performance of the structure.
Preferably, the modulator 300 is a phase shifter.
As shown in
An antenna array 200 is designed and is divided into m antenna subarrays 201 wherein each antenna subarray 201 is controlled by one radiofrequency module 100;
The number n of radiofrequency link units in the radiofrequency module 100 is determined;
A channel model of a frequency band of electromagnetic waves is established;
The analog beamforming parameters P_{A }and the digital beamforming parameters P_{D }are obtained by calculation according to a channel matrix H in the channel model of the frequency band of the electromagnetic waves; and
Beamforming is carried out according to the analog beamforming parameters and the digital beamforming parameters.
Specifically, the antenna array 200 comprises m antenna subarrays 201, the radiofrequency module 100 comprises n radiofrequency link units, and each antenna subarray 201 is connected with one radiofrequency module 100.
The electromagnetic waves are millimeter waves or a terahertz waves.
A structural formula for beamforming is as follow:
y=√{square root over (ρ)}C_{D}^{H}C_{A}^{H}HP_{A}P_{D}s+C_{D}^{H}C_{A}^{H}n_{0 } (1)
In the above structural formula, ρ is the total transmitting power, s and y are transmitted signal and received signal of the number (N_{s}×1) of one data flow, H is the channel matrix of the channel model of the frequency band of the electromagnetic waves, P_{A }and C_{A }are the analog beamforming parameters, P_{D }and C_{D }are the digital beamforming parameters, and n_{0 }is the channel noise. Wherein. P_{A }is a precoded code of an analog domain, C_{A }is a combined matrix of the analog domain, P_{D }is a precoded code of a digital domain, C_{D }is a combined matrix of the digital domain, and C_{D}^{H}C_{A}^{H}n_{0 }is a combined noise vector.
The structure of a coding matrix of a L_{t}×N_{s}dimensional digital domain formed by the total number L_{t }of the radiofrequency link units and the number N_{s }of data flows is as follow:
P_{D}=[P_{D1}^{T }. . . P_{Dm}^{T}]^{T}, (2)
Wherein, P_{Di }is an n×N_{s}dimensional matrix, as for a digital precoded matrix, there is no equalmodulus limitation on the elements of the matrix, and only the transmission power is limited.
The structure of a coding matrix of an N_{t}×L_{t}dimensional analog domain formed by the total number L_{t }of radiofrequency link units and the number N_{t }of antennae in the antenna array 200, is as follow:
Wherein, P_{Ai }is an N_{t}m×ndimensional matrix, and 0 is an N_{t}/m×ndimensional allzero matrix. An analog precoded matrix is realized through a phase shifter network, and thus there is an equalmodulus limitation on the elements in each column of vectors in P_{Ai}.
Beamforming parameters capable of maximizing the performance of the dynamic signal transmission structure are worked out according to preset hardware parameters. Preferably, the hardware parameters here are set with reference to the parameters of the dynamic signal transmission structure based on fulldigital beamforming.
Beamforming is carried out according to the aboveobtained parameters; and the structure of the antenna array 200 in the dynamic signal transmission structure and the number of the radiofrequency link units in each radiofrequency module 100 can be adjusted dynamically to obtain a dynamic signal transmission structure with the hardware complexity lower than the fulldigital beamforming technology, and having the performance approximate to the fulldigital beamforming technology.
In one embodiment, the step of obtaining the analog beamforming parameters P_{A }and the digital beamforming parameters P_{D }by calculation according to the channel matrix H in the channel model of the frequency band of the electromagnetic waves comprises the following steps:
Singular value decomposition is carried out on the channel matrix in the channel model to obtain a solution P_{opt }to a right singularvalue matrix; and
The analog beamforming parameters P_{A }and the digital beamforming parameters P_{D }are obtained by calculation according to the solution P_{opt }to the right singularvalue matrix.
The solution P_{opt }to the right singularvalue matrix, obtained through singular value decomposition carried out on the channel matrix in the channel model, is in a front N_{s }columns of the right singularvalue matrix after the singular value decomposition (SVD) is carried out on the channel matrix H, and the singular value decomposition is an important matrix decomposition in linear algebra, and it is the promotion of eigen decomposition on any matrices, and has important application value in the fields of signal processing, statistics, and so on.
According to the solution P_{opt }to the right singularvalue matrix, the analog beamforming parameters P_{A }and the digital beamforming parameters P_{D }can be obtained by calculation according to the following formula (4):
In formula (4), P_{A }is a value set meeting equalmodulus limitation of P_{A}.
In one embodiment, the analog beamforming parameters P_{A }and the digital beamforming parameters P_{D }are obtained by calculation according to the solution to the right singularvalue matrix based on a sparse coding algorithm. The channel matrix can be divided into in independent parts to respectively solve P_{A }and P_{D }on the basis of the sparse coding algorithm according to the formula (2), formula (3), and formula (4).
In one embodiment, the maximum frequency spectral efficiency of hybrid beamforming of the dynamic signal transmission structure is solved to obtain a relation between the solution P_{opt }to the right singularvalue matrix, and the analog beamforming parameters P_{A }and the digital beamforming parameters P_{D}.
An actual transmission signal is as follow:
x=√{square root over (ρ)}s,
A precoded and combined equivalent channel is as follow:
H_{e}=C_{D}^{H}C_{A}^{H}HP_{A}P_{D},
A combined noise covariance matrix is as follow:
R_{n}_{0}=σ_{n}_{0}^{2}C_{D}^{H}C_{A}^{H}C_{A}C_{D},
An algorithm for maximizing the frequency spectral efficiency of hybrid beamforming of the dynamic signal transmission structure is obtained according to the actual transmission signal x, the precoded and combined equivalent channel H_{e}, and the combined noise covariance matrix R_{n}_{0}. In the structural formula of beamforming, the frequency spectral efficiency of hybrid beamforming is as follow:
Proper P_{A}, C_{A}, P_{D }and C_{D }can be searched out to maximize the frequency spectral efficiency R through formula (5).
In one embodiment, the channel model of the frequency band of the electromagnetic waves is established based on a ray tracing technology.
In one embodiment, the channel model of the frequency band of the electromagnetic waves is a multiuser, multiinput and multioutput channel model.
According to the abovementioned beamforming method, the parameters capable of maximizing the performance of the dynamic signal transmission structure are worked out according to preset hardware parameters, beamforming is carried out based on the beamforming parameters, and the structure of the antenna array in the dynamic signal transmission structure and the number of the radiofrequency link units in each radiofrequency module can be adjusted dynamically to obtain a dynamic signal transmission structure with the hardware complexity lower than the fulldigital beamforming technology and having the performance approximate to the fullyanalog beamforming technology.
The technical characteristics of the above embodiments can be arbitrarily combined, and for the sake of a brief description, not all possible combinations of the technical characteristics of the above embodiments are described. As long as they are not contradictory, all these combinations of the technical characteristics should also fall within the scope recorded in this specification.
The above embodiments are specifically described in detail to show several implementations of invention, but should not be understood as limitations on the scope of the patent of invention. It should be noted that those ordinarily skilled in this field are permitted to make several deformations and improvements without deviating from the conception of the invention, and all these deformations and improvements should also fall within the protection scope of the invention. Thus, the protection scope of the patent of invention should be subject to the appended claims.